There has been a long existing need in the prior art to provide a technique for assembling a two-piece wiring device of the type providing either a switch, junction box or dual outlet receptacle, and of the type wherein multiple conductors are electrically connected to insulation penetrating electrical contacts contained in the wiring device during assembly of the two-piece wiring device. Particularly when the two-piece wiring device is assembled and simultaneously connected electrically to an elongated conductor by forcibly urging a cover portion and a base portion together a sturdy force-applying tool is required. Desirably the tool should be inexpensive, rugged, easy to use and of a common or standard design for availability. The wiring device itself should be adapted with assembly features that readily accommodate standard assembly tools.